Evaluation of Merlot and Malbec Clones

Data collected in 1997 in Merlot showed similarities to previous years. Clone 08 had the lowest yield (8.0 kg/vine) as a result of fewer berries per cluster and smaller berries. It also had the greatest pruning wt (1.5 kg/vine) as a result of heavier, not more, shoots. Clones 01, 03, 06 and 09 were very similar in yield (about 10 kg/vine) and growth (1.2 to 1.4 kg/vine) and their components. With the lower crop and greater pruning wt, clone 08 had a much lower yield:prunings ratio (5.2) versus the other clones (7.2 to 8.2). Wines were made in cooperation with Duckhorn Vineyards. All wines exhibited a reduced character, as they did also in 1996, inhibiting the ability to draw distinctions among clones. Steps will be taken in 1998 to avoid this problem. If treatment lots improve over time, more distinctions will be made through sensory panels. Three clones of Malbec, FPMS 04, 06 and 08, were compared on two rootstocks, 5C and 11 OR. Malbec recovered from the disastrous fruitset in 1996 where all clones yielded less than 0.5 tons/acre. Yields in 1997 were 6.1 to 8.8 tons/acre in 1997. Under normal conditions, clone 08 shows a tendency to over-crop as a result of 2.37 clusters per shoot and average cluster wt 60%greater than either clone 04 or 06. Therefore, most of the Malbec 08 was thinned to 1.7 clusters per shoot, except for some unthinned vines kept as a control. Comparison of thinned and unthinned Malbec 08 indicate that the crop was reduced from 11.6 to 8.8 tons/acre and Brix at harvest improved from 19.9 to 22.5. Pruning wts ranged from a low of 1.59 kg/vine for thinned 08 to 2.33 kg for clone 06. Unthinned 08 pruning wt was 1.28 kg. The only effect of rootstock was that 110R had more clusters (64) than 5C (58). A significant effect of rootstock was not seen for any other growth or yield components, nor were there any rootstock x clone interactive effects.